Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BREATH ACTUATED NEBULIZER
FIELD OF THE INVENTION
[0001] This disclosure pertains to nebulizers for the administration of
inhaled aerosol drugs.
BACKGROUND
[0002] In the field of respiratory devices, nebulizers are important
devices
used for the inhalation of drugs in the form of an aerosol to patients in need
of a
drug administered directly into the lungs. A nebulizer employs an apparatus
that
generates an aerosol or mist from a solution (usually an aqueous solution) or
suspension of a drug. The mist may be an aerosolized suspension or an atomized
suspension of drug, meaning micro-droplets suspended in air, medical oxygen,
or
other inhalable gas. The aerosol is conveyed to the mouth and/or nose of a
patient
and inhaled into the lungs. In some cases, the mist is conveyed to the lungs
through
a mouthpiece. In other cases, the nebulizer may be coupled to an inhalation
mask.
[0003] Several nebulization technologies are known, including gas-jet,
ultrasonic, and vibrating mesh nebulizers. This disclosure pertains to gas-jet
nebulizers, which operate using a Venturi, wherein a jet of pressurized gas
(air or
other suitable gas, such as medical oxygen) is directed over an orifice on a
capillary
that is connected to a reservoir containing a drug in aqueous solution. The
Venturi
creates a localized low pressure zone that draws the drug solution out of the
capillary orifice and into the air jet, where the liquid is atomized by a
shearing
effect. Typically, a baffle is employed in the jet effluent to assist in the
formation of
appropriate size droplets in the nebulized stream. In addition, a baffle
prevents
large droplets from exiting the device, so that only aerosol micro-droplets of
drug
containing solution exit the device. Still further, in many nebulizer designs,
a baffle
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may be required to deflect the low pressure zone created by a Venturi jet over
a
liquid orifice in communication with the drug reservoir. In such designs, the
baffle
is required to draw the liquid into the stream of pressurized gas that causes
nebulization of the liquid. An example of such a nebulizer is disclosed in
U.S. Patent
4,588,129. The aerosol is then inhaled by the patient. Typically, the aerosol
production is continuous, so a vent is typically provided to ensure that the
pressure
differential created by the jet operates continuously and consistently. The
drug
reservoir in nebulizers is usually a cone, cup, or bowl-shaped vessel into
which a
sterile aqueous solution of the drug is added.
[0004] Other nebulizer methods besides gas-jet nebulizers are known, for
example ultrasonic nebulizers and vibrating mesh nebulizers.
[0005] Typical drugs used with nebulizers are drugs for the treatment of
asthma and obstructive pulmonary diseases, but other pulmonary and systematic
medications may be administered by inhalation with nebulizers. For example,
albuterol (called salbutamol in many countries), used for treating asthma and
bronchospasm, may be administered as a nebulized solution. Another example is
pentamidine, a drug used to treat Pneumocystis carinii pneumonia (PCP) (also
called Pneu,mocystis jirovecii). Many other medications are useful or
potentially
useful as inhaled drugs and can potentially be used. with a nebulizer.
[0006] Nebulizers are particularly useful for the administration of
inhaled
drugs to small children, elderly, unconscious, or disabled patients who cannot
coordinate their breathing or take instruction on the use of coordinated
inhalation
devices, such as a metered dose inhaler. Also, nebulizers may be used with an
inhalation mask for patients who cannot use a mouthpiece to inhale the drug.
With
a nebulizer, the dose of drug is administered to the patient over a period of
several
minutes, and possibly ten to twenty (or more) tidal or slow deep inhalations
per
minute, so breathing coordination is not required.
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[0007] Nebulizers are typically equipped with a mouthpiece that a patient
can insert in their mouth, making an airtight seal with their lips while
inhaling
through the mouth to ingest the nebulized medication into the lungs. In the
case of
patients who cannot hold a mouthpiece in their mouth or close their lips round
the
mouthpiece to create a seal, an inhalation mask may be used with a nebulizer.
An
example of such a mask is disclosed in PCT International Application
WO 2012/173993.
[0008] In breath-actuated nebulizers, nebulization of the drug only occurs
during inhalation by the patient. Breath-actuated nebulizers have a means for
stopping the nebulization or flow of aerosol during exhalation or other
intervals
when the patient is neither inhaling or exhaling. Such devices are known, for
example, from Denyer in United States Patent RE40591, and Grychowski et al.,
in
U.S. Patents 5,823,179 and 6,644,304. A breath-actuated nebulizer has been
marketed in the United States under the brand name AEROECLIPSE@ by
Monaghan Medical, and by Trudell Medical International in other countries.
[0009] Breath-actuated nebulizers may have significant advantages over
conventional nebulizers. In conventional nebulizers, the drug is aerosolized
continuously regardless of whether the patient is inhaling or not.
Conventional
nebulizers typically are vented to the atmosphere, so aerosol that is not
inhaled is
vented to the air in front of the patient. This wastes drug, and exposes
others
(including caregivers) in the vicinity to the aerosolized drug. In addition,
the dosage
is impossible to precisely determine because of this drug loss. In many cases,
these
shortcomings are not a problem, due to the low cost of conventional
(continuous)
nebulizers, and the low toxicity and low cost of drug of many of the drugs
used in
conventional nebulizers.
[0010] However, in the case of expensive drugs or drugs that may be toxic
or sensitizing to others in the vicinity of the patient, conventional
nebulizers are
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much less desirable than a breath-actuated nebulizer. With a breath-actuated
nebulizer, the dosage can be precisely metered, and very little of the drug is
wasted,
since nebulization is stopped when the patient is not inhaling.
BRIEF SUMMARY
[0011.] In an embodiment, this invention provides a breath triggered gas
jet
nebulizer comprising a generally cylindrical body in a horizontal orientation
to the
patient. Within the body is a Venturi configured to nebulize a solution of a
drug
stored in a reservoir. Within the body is a shaft integrated with a baffle and
diaphragm that moves horizontally in response to the breathing of a patient.
When
the patient is inhaling the diaphragm flexes shifting the baffle toward the
patient
and over the Venturi, allowing nebulization to occur. When the patient's
inhalation
stops, the diaphragm flexes to a default position in which the baffle is
shifted to a
position distal to the Venturi, thereby stopping the nebulization.
DESCRIPTION OF THE DRAWINGS
[0012] Figure 1A is a cross-section of the nebulizer in the nebulization
mode.
[0013] Figure 1B is a cross-section of the nebulizer in the non-
nebulization
mode.
[0014] Figure 10 is a detail cross-section of a portion of Fig. 1B
[0015] Figure 2A is an exploded view from an anterior viewpoint.
[0016] Figure 2B is an exploded view from a posterior viewpoint.
[0017] Figure 3A is a perspective view of the assembled nebulizer from an
anterior viewpoint.
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[0018] Figure 3B is an elevation view of the front (anterior) end of the
nebulizer.
[0019] Figure 3C is a perspective view of the assembled nebulizer from an
posterior viewpoint.
[0020] Figure 4A is a perspective view of the inventive nebulizer with an
inhalation mask connected to the airway of the nebulizer.
[0021] Figure 4B is a different perspective view of the inventive
nebulizer
with an inhalation mask connected to the airway of the nebulizer.
[0022] Figure 5A is a perspective view of the inventive nebulizer with a
mouthpiece connected to the airway of the nebulizer.
[0023] Figure 5B is a different perspective view of the inventive
nebulizer
with a mouthpiece connected to the airway of the nebulizer.
DETAILED DESCRIPTION
[0024] The nebulization action in the gas jet nebulizers disclosed herein
for
administering medication to humans or animals by inhalation depends on a
device
with a reservoir containing a solution with a drug dissolved therein, and a
Venturi
effect with a high pressure jet orifice and one or more liquid orifices
adjacent to the
jet, wherein a baffle or deflector impinges on the jet a short distance above
the jet
orifice. One or more liquid orifices adjacent to the Venturi orifice are in
communication with liquid tubes or capillaries fed by a drug reservoir
containing a
solution of drug. The nebulization or aerosolization (these terms are used
interchangeably herein), presumably occurs because the baffle deflects the low
pressure zone created by the Venturi over the liquid orifices. Without being
bound
by any theory of operation, it is believed that the reduced pressure created
by the
Venturi jet impinging on the baffle draws the drug solution through the liquid
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orifices, and the jet aerosolizes the liquid as it exits the liquid orifices
from shearing
effects. The baffle typically also performs a secondary function of deflecting
large
droplets and forcing them back into the drug reservoir, since in a drug
nebulizer,
only very small droplets that freely float in air are desired as an inhaled
aerosol.
Without the baffle, the liquid orifices are presumably not subject to the
effect of the
Venturi low pressure zone and no liquid is drawn out of the liquid orifices,
and no
aerosolization occurs. Thus, in this invention, a movable baffle is provided
in a
horizontal plane, such that when the baffle is directly over the Venturi,
nebulization
occurs, and when the baffle is moved horizontally away from the Venturi,
nebulization stops. In this invention, by moving the baffle into a nebulizing
position
in response to the inhalation of a patient, the nebulization only occurs when
the
patient is inhaling, and no nebulization occurs when the patient is exhaling
or
otherwise not exerting an inhalation. This movement of the baffle that creates
or
stops nebulization is termed "breath triggered" or "breath actuated" (which
terms
are used interchangeably) nebulization.
[0025] In an embodiment of this invention, a breath triggered nebulizer is
provided for the administration of inhaled medication to a patient, said
nebulizer
having horizontal and vertical axes, comprising a horizontally oriented
cylindrical
body defining an upper chamber airway; a vertically oriented lower chamber
having
therein a liquid reservoir containing a medicament in solution, wherein said
liquid
reservoir defines the horizontal axis; a pressurized gas inlet port in fluid
communication with a gas jet; a liquid channel surrounding the gas inlet port,
said
liquid channel in fluid communication with a liquid orifice, wherein the gas
jet is
adjacent to the liquid orifice, and the gas jet is oriented vertically; a
horizontally
movable baffle comprising a first position at a predetermined distance from
the gas
jet such that a pressure differential is created in the liquid channel that
draws
liquid through the liquid channel and causes nebulization by the interaction
of the
gas jet and liquid orifice; wherein the baffle has a second default position
distal
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from the gas jet such position at a distance from the gas jet so that the
pressure
differential is insufficient to draw liquid into the liquid channel, and no
nebulization of the liquid occurs; wherein the baffle movement is controlled
by a
horizontal channel between the first and second positions at a fixed vertical
distance relative to the gas jet; and wherein the baffle is moved from the
second
position to the first position by the inhalation by the patient, and the
baffle shifts to
the second position when the patient is not inhaling.
[0026] Thus, the inventive nebulizer 10 in the Figures has defined
horizontal and vertical axes. In one aspect, the horizontal axis is defined by
the
drug reservoir 112, which must generally remain generally level because it
contains
a liquid. In another aspect, the horizontal axis may be defined by a line
through the
center of the generally cylindrical body 100, from the airway end 104 to the
back of
the apparatus at cap 130. Thus, as shown in Figs. 1A and 1B, the horizontal
and
vertical axes are as drawn, i.e., the vertical axis is top to bottom, and the
horizontal
axis is right to left. Thus, cap 150 is at the top of the device, and lower
body 110 is
at the bottom of the device.
[0027] Body 100 of the nebulizer 10 comprises a main section that is
cylindrical in shape, is oriented horizontally, and defines an interior
chamber 101.
The ventral side of body 100 has a circular opening 106 connected to lower
body
110. Lower body 110 includes a drug reservoir 112 that in operation would be
filled
with a liquid medication. Reservoir 112 is a cup shaped vessel that narrows at
the
bottom and feeds the drug solution into opening 320 for inspiration into the
Venturi,
[0028] The Venturi is integral with lower body 110. The Venturi comprises
a pressurized gas inlet stem 1.16 and pressurized gas tube 115. At the top of
tube
115, at least one liquid window 330 is provided, with section 332 above the
window.
Tube 115 narrows in the conical section 117, leading to Venturi orifice 310. A
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passageway 336 is defined between section 332 and section 117. At the top of
passageway 336 is ono or more liquid orifices 312 through which the drug
solution
will pass during nebulization. Stem 144 fits over tube 115, defining a narrow
passageway 335 for the drug solution to pass during nebulization. The drug
solution
is fed into passageway 335 through an opening 320 at the bottom of stem 144.
During nebulization, the drug solution is drawn through opening 320, up
passageway 335, and through windows 330. The drug solution then moves into
passageway 336 and exits from orifices 312. The drug solution is then
aerosolized in
the space of chamber 101 on exposure to the high velocity low pressure local
environment in the Venturi during nebulization.
[0029] In an embodiment, the Venturi orifice 310 and the orifices 312 are
situated on a planar surface 313 and. all of orifices 310 and 312 are on the
same
plane.
[0030] The dorsal side of body 100 may contain a circular opening 108
which is covered by top cap 150. Top cap 150 is intended to be easily
removable, and
can be used to add the drug solution to the reservoir 112 with a pipette or by
simply
pouring a solution of drug into the reservoir 112.
[0031] The anterior end of body 100 (the end closest to the patient)
comprises opening 104 which defines the airway 105 by which aerosolized drug
is
exhausted from the nebulizer during inhalation into the mouth or nose of a
patient.
The aerosolized drug then travels to the lungs of the patient during
inhalation. In
an embodiment, baffle 109 is situated in the airway aft of opening 105. If
present,
baffle 109 blocks about the lower third of opening 105, and helps to ensure
that only
freely floating aerosol particles are inhaled by the patient. Baffle 109 helps
to block
the ingestion of larger aerosol particles from being inhaled.
[0032] In an embodiment, as illustrated in the drawings, opening 105 is in
communication with adapter 400 and swivel adapter 410. A mouthpiece or mask
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may be connected to airway 430 on swivel adapter 410 in this embodiment. Also
shown is exhaust valve 420, in the illustrated embodiment integrated to
adapter
400. An embodiment of exhaust valve 420 is shown with flap 422, made from a
flexible rubber material that provides a tight seal during inhalation but
flexes open
to exhaust exhaled air during exhalation. Other configurations of the exhaust
valve
are possible. An exhaust valve is necessary in this nebulizer because there is
no
other vent or pressure equalization provided in body 100 for exhaled air.
[0033] The posterior end of body 100 comprises a circular opening 102
that
is connected end cap 130. A series of vents 132 are in cap 130. A series of
one-way
vents 132 are in cap 130 that permit air to enter to equalize pressure during
inhalation, but are sealed during exhalation.
[0034] Channel support 140 is an integrated part that includes
vertical
shaft 144 and cap portion 142. Shaft 144 defines a pipe that nests over gas
tube
115. The space between shaft 144 and tube 115 is liquid passage 335. Cap
portion
142 contains baffle guide channels 148 and 149. Alignment tab 146 protrudes
from
vertical shaft 144 on the left side as illustrated in Fig. 2A, and serves to
align
support 140 with respect to the movable baffle. Tab 146 fits into slot 147 on
lower
body 110.
[0035] Within body 100 is integrated shaft assembly 200, which
includes
diaphragm 210 and the Venturi baffle 202. Diaphragm 210 is supported
peripherally by ring 212, which is torsionally inflexible, and nests in
indents 122,
part of body 100. The diaphragm 210 is made from a flexible material such as a
soft
rubber, and can easily flex in response to the patients breathing. The center
of
diaphragm 210 is connected to shaft 200. The anterior end of shaft 200
contains
supports 205 and 206. Guide skid 204 is connected to 205, and baffle 202 is
connected to 206. The posterior end of baffle 202 contains tab 203, that acts
as a
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backstop, preventing further forward motion of shaft 200 during inhalation,
when
the shaft moves forward.
[0086] This nebulizer is termed "breath triggered" because the action of
inhalation during use starts nebulization of a drug, and nebulization of the
drug
ceases when inhalation ceases, either during exhalation or any other point
when the
patient is not inhaling, that it, drawing air into the patients' lungs
naturally.
During inhalation, the breathing action creates a negative pressure in the
chamber
101 of the nebulizer 10. This flexes the diaphragm 210 forward, which moves
baffle
202 from the default non-nebulization position to the nebulization position,
by
shifting the integral shaft 200 and movable baffle 202 to a position directly
over the
Venturi jet, thereby causing aerosolization to occur when the liquid orifices
312 are
subject to the high velocity low pressure local environment from the Venturi.
This
movement is illustrated by cross-section views in Figs. 1B and 1A. Fig. 1B is
the
default, non-inhalation position. The diaphragm is biased to the position as
shown
in Fig. 1B when no inhalation is occurring. During inhalation, the negative
pressure
in chamber 101 draws diaphragm 210 forward, as shown in Fig. 1A, and moves
shaft 200 and baffle 202 to cause nebulization to occur. The diaphragm must be
designed to be sufficiently sensitive to low inhalation flow velocities, for
example
from highly diseased persons with very weak inspiratory ability, or small
children,
yet still provide sufficient force to move the shaft to the nebulization
position. In an
embodiment, the diaphragm may be designed to move within a range of inhalation
flow rates of 0.5 L/min in new born infants to 15L/min in adults.
[0037] When inhalation ceases, the diaphragm flexes in a posterior
direction to its default position, returning to the configuration shown in
Fig. 1B,
drawing movable baffle 202 rearward so that the Venturi jet is vented into the
space between supports 205 and 206. Without the baffle directly over the
Venturi,
no nebulization occurs, because the jet vents directly upward, and the liquid
orifices
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312 are not subject to the Venturi effect, so no liquid is drawn through the
orifices
312.
[0038] The vent ports 120 equalize pressure during inhalation, preventing
a vacuum from developing in the main body of the nebulizer. Flexible flaps
220,
which are integral with the diaphragm 210 rest in indents in section 122, and
cover
ports 120 from the interior chamber 101. During exhalation or when breathing
is
relaxed, the flaps prevent air and aerosolized drug in the interior chamber
101 from
escaping from the nebulizer. During inhalation, the negative pressure in the
interior chamber 101 opens the flaps to equalize the air pressure in the
chamber
101.
[0039] In an embodiment, a noise making feature may be provided that
makes a clicking sound during inhalation. As shown in the figures, this may
comprise protrusion 230 that rests in cavity 134 on the interior of end cap
132.
During inhalation, when the shaft assembly 200 is drawn forward, the action of
protrusion 230 moving in cavity 134 may make a clicking sound. In an
embodiment,
when the shaft assembly 200 moves back to its default position during
exhalation,
230 and 134 hit each other making a clicking sound.
[0040] The interface with the inventive apparatus and the patient is a
mouthpiece or inhalation mask. A mouthpiece may comprise various embodiments.
In an embodiment, a mouthpiece may be a generally cylindrical or ovoid (in
cross
section) appendage suitable for insertion into the mouth of the patient. The
patient
then wraps his or her lips around the mouthpiece to make a seal and proceeds
to
inhale and exhale to receive the nebulized drug. In another embodiment, a
mouthpiece may have a flattened portion for insertion into the mouth and lips.
[0041] In another embodiment, an inhalation mask may be employed that
covers the mouth and/or nose of the patient. The mask would have a suitable
inlet
for connecting to airway 105 to receive the nebulized medication that is
transmitted
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to the mouth and/or nose of the patient. Small children, in particular, are
obligate
nasal breathers. In the case of an inhalation mask, an exhaust valve is
mandatory,
because there is no pressure equalization outlet in the inventive nebulizer
apparatus to vent exhaled air. Such an exhaust valve may be integrated into
the
mask, or it may be on a linking part between the nebulizer and the mask, shown
for
example as part 420 in the drawings. With any exhaust valve embodiment, a
further optional embodiment is a filter to trap and prevent substantially all
of the
active drug from entering the outside air in front of the patient. In some
case, active
drug can harm nearby persons including caregivers, and may even harm the
patient, for example by causing eye irritation. The use of a filter can
prevent this
problem.
[0042] Various embodiments of the inventive nebulizer and a mouthpiece or
inhalation mask are shown in Figs. 4 and 5. Figs. 4A and 4B show an inhalation
mask connected to the inventive nebulizer with a swivel adapter. A variety of
masks may be employed with the inventive nebulizer. The mask shown in Figs. 4A
and 4B is described in international patent application PCT/US2012/042055, and
has a soother device orifice, through with a nipple may be inserted for use
with a
small child who would suck on the nipple while inhaling medication through the
mask with an airway aligned with nose of the patient. In another embodiment
(not
shown), the mask may not have a soother device orifice.
[0043] Figs. 5A and 5B illustrate the nebulizer with a mouthpiece that a
competent older child or adult would typically use. The mouthpiece is inserted
into
the mouth of the patient and the patient forms a seal around the mouthpiece
with
their lips while inhaling a drug using the nebulizer. By the term "competent"
it is
meant here that the patient is conscious and can accept and understand
instructions.
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[0044] By the term "medicament" as used herein is meant a drug suitable
for administration directly into the lungs of a patient.
[0045] This invention provides both a nebulizer apparatus 10 and a method
of administering a drug to a patient with a nebulizer 10. In the method of
administering a drug to a patient, a solution of a drug is added to reservoir
112
through opening 152, a source of pressurized medical gas, such as air or
medical
oxygen is connected to stem 116. In various embodiments, a mouthpiece fitted
to the
inventive nebulizer is inserted into the patients mouth, or a mask is
connected to
the nebulizer that is held by a caregiver over the mouth and nose of a
patient.
When the patient inhales, the nebulizer 10 will provide atomized drug that
will
enter the lungs of the patient. When the patient is not inhaling, such as
during an
exhalation or during periods when the patient is neither inhaling nor
exhaling, the
atomization stops. Accordingly, there is minimal wasted drug as compared to
conventional nebulizers that nebulize drug continually regardless of whether a
patient is inhaling or not, and the dose of the drug can be more accurately
determined, since there is minimal wastage.
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